Well, my currently crude numbers are 0.054" valve to piston with the Colt Stage 2 cam. That IS a relief since that cam has more lift to it. BUT, is should not be surprising since my heads are at the upper end of the deep valve recession tolerance anyway. The piston to head clearance is 0.035". That maybe fine. B.

 

Ha..... Ha......Ha.....

Jack, try a colonic once in a while. LOL B.

 

Are you doing this with solid lifters or hydraulic lifters?

Night....

 

I'm using factory hydraulic roller lifters. B

 

In case you were curious. This link will take you right to the point in time where they are cracking the rod.

 

That WAY cool Sean, thanks for sharing. B.

 

There's another good video of showing this done in production, but I watched that years ago.

 

The problem with using hydraulic lifters is that they don't have the pressurized oil to fill the chambers while rotating through, which affects the lash and the indexing. So as you are trying to correlate the max piston height with the initial intake opening or closing of the exhaust valve, you can be off with both lift and the ramp's start and endpoints due to excessive movement of the plunger.

I stacked the lifters and made an adjustable pushrod to check; my video was to show how to do that and provide values so people could check the protrusion and recession and not have to do the work. But that's a big trust leap.

 

Ok, did things a little different today. I took apart two of my old, but in great shape, lifters and stuffed then with washers until there was no internal movement. Installed those and ran another clearance check, this time using clay. Pulled the heads back off and started slicing and dicing to get some solid numbers taking multiple measurements as I went. Deck clearance with the, effectively, solid lifters is 0.030" piston to head. Is that good? I can't seem to find a spec on that. Valve to piston clearance was between 0.040" and 0.045" depending on intake or exhaust. So I know those numbers are good.

I again checked piston protrusion. I got 0.028" on one bank and 0.031" on the other. So 0.003" difference between each side. I don't think that will be a problem as this is within specs of 0.034" max. I got these numbers by using feeler gauges at the top and bottom of the pistons to keep them from rocking in their bores. And taking a measurement directly over the wrist pins. Oh, by the way, I checked the piston skirt to bore spec and it's between 0.0025" and 0.003".

So I guess my only real question is; Do I have enough clearance between the top of the pistons and the bottom of the heads? Thanks, B.


Using an old piston and a sharp blade, I cut out a piece of saran wrap to cover the clay. This keeps it from sticking to the head and valves when I rotate the engine over to make impressions.


After the impression is made, gently lift the saran wrap away and start slicing and dicing to take measurements.



This is just one of MANY deck clearance slices I made. Looking for consistency.


This is one of MANY valve clearance slice and dices. Again, I'm looking for consistency.

 

As long as your piston protrusion is under spec (0.034") and you are using OE or FelPro gaskets, you won't have piston to head contact. Lifters have no effect on that.

If your valve to piston clearance is 0.040 to 0.045", you are doing better than me.

 

I have Fel Pro. I used my old, 200 miles on them, head gaskets to get these numbers. I just want to make darn sure the piston to head clearance is good. Pondering if I should have the machine shop take ten off the piston tops for safety margin. I don't know how much these things "grow" when they get hot. It's a little unsettling there is no spec for this distance.

I wonder if Asheville has ever checked this measurement? They have coined in on this thread early on. I wonder if they are still following? B.

 

The OE gasket is thinner and the max spec is 0.034” for protrusion. I wouldn’t overthink this.

 

You're right Jack. I am prolly thinking too much.

So, on that note, I did some more work today. Finished building my piston/rod assemblies. Then installed same. Did another round of plasti-gauge, but this time on the rod bearing clearances. They are nice and tight, with all four rod journals being right at 0.0017"ish. Less than two thousandths and more than one thousandths. Encouraging. Then I buttoned up the bottom end. Flipped the old girl over so she was right side up. I re-checked my piston protrusion on the remaining 6 pistons. They are in line with the first two. Now to prep for installing the top end. B.



Plasti-gauge.





Hopefully the LAST time she will see the light of day for a very very long time.








Can't hurt right? LOL

 

Please check the surface roughness of the block surface before mounting the heads. I would be concerned about the scoring.
Jack had once shown this in a video. For me it seems to be to "rough".

 

I have a new 8" stone, I can hit it real fast and see what it looks like. B.